Union leaders have threatened to disrupt the tournament if the government refuses to back down, with protests on railway tracks one tactic at their disposal.

Vidalies told Europe 1 radio that this would be "an action against France and the French people" and that he hoped this wouldn't happen.

Philippe Martinez, whose left-wing CGT union is leading the strikes, said he was due to meet Labor Minister Myriam El Khomri on June 17, three days after a planned national protest against the reform.

"That's what we have been demanding for months. It's high time," Martinez told Reuters. "It's better if we talk."

French President Francois Hollande has also waded into the row, saying everyone had a duty to ensure the tournament passed off without incident.

"I appeal to everyone's sense of responsibility because if the state must do its duty - and it will, it will take all the measures that are necessary," he said.

"At the same time, it is also necessary that those who are taking part in actions, or who are organizing them should also shoulder their responsibility, so that this great event can be a shared popular festival."